title: Evaluation of a rapid detection method of clarithromycin resistance genes in Mycobacterium avium complex isolates.
abstract: OBJECTIVE
  Clarithromycin is the key drug in the various treatment regimens of Mycobacterium avium complex (MAC) diseases, and is the only drug for which drug susceptibility has been shown to correlate with clinical response in these diseases. A point mutation at either positions 2058 or 2059 of the 23S rRNA gene has been reported to occur in high-level clarithromycin-resistant isolates. In this study, we examined the correlation between the results from a drug susceptibility test and the mutation of the 23S rRNA gene involved in drug resistance in MAC. Furthermore, we adapted a rapid detection method using amplification refractory mutation system (ARMS)-PCR to identify mutations in the 23S rRNA gene in MAC isolates.
  
  
  METHODS
  Using a microdilution method based on the NCCLS/CLSI recommendation, the MIC of clarithromycin was determined for 245 clinical MAC isolates. Of these, 219 clarithromycin-susceptible and 26 clarithromycin-resistant strains were analysed by sequencing of the 23S rRNA gene and ARMS-PCR.
  
  
  RESULTS
  The drug susceptibility test revealed a bimodal distribution of MICs for both the susceptible and resistant strains. Sequence analysis of the 23S rRNA gene revealed that all of the clarithromycin-susceptible strains were wild-type whereas 24 of the clarithromycin-resistant strains were mutant type. The sensitivity of the sequence and ARMS-PCR analyses was 92.3% and 84.6%, respectively, and the specificity of both was 100%.
  
  
  CONCLUSIONS
  We found a correlation between MICs of clarithromycin and 23S rRNA gene mutations. ARMS-PCR for 23S rRNA mutations of MAC isolates is useful for rapid detection of clarithromycin resistance.
authors.affiliation: Department of Clinical Research, National Hospital Organization, Higashinagoya National Hospital, and Department of Microbiology, Faculty of Pharmacy, Meijo University, 5-101 Umemorizaka, Meito-ku, Nagoya, Aichi 468-8620, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Inagaki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yagi
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Taku
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Moriyama
authors.forename: Kei-ichi
authors.initials: K
authors.lastname: Uchiya
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nikai
authors.forename: Kenji
authors.initials: K
authors.lastname: Ogawa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017291:Clarithromycin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D015269:Mycobacterium avium Complex / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods*; D012329:RNA, Bacterial / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D014376:Tuberculosis / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin